The present invention relates to a method and apparatus for effecting an ionic change in fluid to decolor the fluid or to carry out a REDOX reaction, for example.
One of the major problems with fluid containment systems is the deposition of metal oxides and other metal compounds on the inner surfaces of the containment system. These deposits of various metal oxides, in particular, iron oxides, and other metal compounds build up over a period of 5 to 10 years. After approximately 5 years, when a tap is first opened after a certain down time, for example, in the morning after the system has been shut down during the night, the first water flowing from the system exhibits the red/brown color of the iron oxides. After perhaps 10 years, this initial water can become quite strongly colored and a considerable amount of time is necessary to flush the system before suitably clear water can be obtained.
U.S. Pat. No. 4,902,391 discloses a method and apparatus developed by the present inventor for ionizing, with great efficiency, fluid having a high dissolved solid content for the purpose of eliminating the problems caused by the deposition of substances, such as ferric particles, on the inner surface of fluid piping. According to the method and apparatus disclosed in U.S. Pat. No. 4,902,391, two electrodes of electrically conductive material having different electrochemical potentials, e.g. aluminum and carbon electrodes, are used to provide a voltaic cell structure which employs fluid to be treated as the electrolyte of the cell, whereby the fluid is ionized owing to the electric potential of the electrodes. U.S. Pat. No. 3,342,712 and U.K. Patent No. 1,288,552 also disclose similar apparatus using two electrodes for the treatment of fluids.
Such apparatus are effective for removing an iron compound scale. However, the action of removing such a scale is relatively slow.
To overcome this disadvantage, the present inventor has developed a dual system using three electrodes which has been made the subject of U.S. patent application Ser. No. 07/657,813. In this system, a third electrode of a metal, for example iron, is used to produce a concentration of metal ions in the fluid to thereby inhibit large amounts of the same ions of other iron compounds from being released into the fluid. Such a three electrode device still employs two of the electrodes to keep the system clean by slowly removing the deposited metal compounds, but the coloration of the fluid is greatly reduced owing to the third electrode to allow normal use of the fluid.
In the research conducted with the dual system having the three electrode design, a satisfactory performance was achieved when the third electrode was made of iron and was incorporated within the original device having only two electrodes. However, when tests were made with an electrode directly in contact with a carbon electrode, but not contained within the body of the original device, the performance was not satisfactory and resulted in even worse coloration of the fluid. This lead to the thinking that the fluid flow and sequence in which the fluid contacted the electrodes could be a vital factor.
A prototype device was made in which two electrodes, carbon and iron, were disposed within a plastic tube such that fluid flowing through the tube would contact the electrodes in sequence. With such a model, a very obvious and strong effect was observed of inhibiting a piece of rusted iron immersed in the fluid from coloring the fluid.
For comparison testing, two pieces of similarly sized iron with similar rust conditions were provided, one piece being immersed in fluid together with the device having the two electrodes described above, and the other piece being immersed in a similar amount of fluid. After about five hours, the fluid with only the rusted iron piece was showing evidence of coloration which then became stronger over time. However, with the device comprising the two electrodes, the fluid showed only slight coloration after three days.
In order to confirm the effect attributed to the positioning of the electrodes, test devices were made as follows:
(1) A tubular iron section positioned coaxially between two tubular carbon sections and inserted into a length of plastic (insulating) tubing, so that the fluid could only contact the internal walls of the tubular sections. All tubular sections had similar inner and outer dimensions and the iron section was in direct contact with the carbon sections. PA1 (2) A tubular carbon section positioned coaxially between two tubular iron sections and inserted into a length of plastic tubing as in item 1. PA1 (3) An iron rod with carbon rods attached at each end of the iron rod. PA1 (a) the electroconductive materials (iron and carbon) of the electrodes were placed in direct physical contact, PA1 (b) a resistor was connected between the electroconductive materials (iron and carbon) of the electrodes, and PA1 (c) the electroconductive materials (iron and carbon) of the electrodes were isolated both physically and electrically so that the fluid provided the only electroconductive connection between the electrodes.
Three small test containers were set up with equal volumes of fluid (water). Test devices (1), (2), and (3) were immersed in each of the test containers, respectively. The axial dimension of the pieces of plastic tubing of test devices (1) and (2) was oriented vertically with the upper end of the pieces of plastic tubing being located below the surface of the fluid in each of the respective containers. This caused the fluid to flow downward through the tubing as was observable by changes in coloration of the fluid described below. In addition, pieces of rusted iron having similar sizes and similar rust conditions were immersed in each of the test containers together with the test devices. The test units so constructed were allowed to stand and were examined from time to time to observe changes in color in the fluid.
Observations of the three test units described above show that the test unit with device (3), i.e. with the exposed carbon and iron rod structure, provided no inhibiting effect on the coloration of the fluid.
Test device (1) showed a strong control in inhibiting the coloration which would otherwise be caused by the iron oxide, whereas test device (2) showed an apparent increase in the rate and degree of coloration.
In order to fully confirm the results provided by these test devices, the fluid was drained from each container and the containers were carefully washed and cleaned to remove any residual stains of the iron oxide. The rusted test pieces of iron were each washed and the same test device with the same piece of rusted iron were then placed back into the container in which they had been previously placed. New fluid (water) was then added in equal volumes to the containers.
This cleaning of the test devices, the rusted iron and the containers and the replenishment of the containers with fresh fluid was repeated several times in order to confirm the reliability of the test results.
The above test results verified that a combination of carbon/iron/carbon electrodes in a tube, which ensured that the fluid contacted the carbon/iron/carbon material in that order, inhibited the colorization of the fluid. The other combination of iron/carbon/iron electrodes in a tube did not inhibit coloration, but could be useful in other applications. Finally, a combination of merely carbon/iron electrodes simply immersed in the fluid with no tube to ensure sequential contact of the fluid with the carbon/iron materials could be disregarded.
It is to be noted that the test device having the carbon/iron/carbon electrodes had been selected in order to investigate a device in which the fluid could flow in either direction through the tube. However, tests were also made with only iron and carbon electrodes provided within a tube of plastic which would be useful in a system in which the fluid could only flow in one specified direction. Tests with the combination of iron/carbon electrodes provided a satisfactory effect of reducing the coloration of the fluid when the fluid first contacted the iron electrode and then exited through the tube after contacting the carbon electrode.
Having confirmed that a necessary condition for decoloration is that the fluid exits the tube after contacting only the carbon electrode, the next point investigated by the present inventor was the conductive relationship between the carbon and iron electrodes. For this purpose, further tests were carried out with devices employing only a carbon electrode and an iron electrode provided within an insulating tube, with the fluid flowing in a specified direction through the tube so as to first contact the iron electrode and then contact the carbon electrode before flowing from the tube.
The following conductive relationships were established in the above-mentioned test devices:
The series of tests run with the devices above all showed satisfactory results in particular applications. For example, device (a) was suitable when the iron oxide coloration was severe and device (c) was suitable in the early stages of coloration.
From the above-described tests carried out by the present inventor, the present inventor has posited that an ionic change in the fluid can be attributed directly to the sequence in which the fluid flows over the electroconductive materials of the electrodes, irrespective of the manner in which the electrodes are electroconductively connected, although such an electroconductive connection seems to have a control on the rate of ionic change. Specifically, it appears that the material of the exit electrode can be selected to effect a desired ionic change in the fluid based on known properties (composition) of the fluid.